We have 10 times more microbes than human cells in our bodies. Or this, which is almost the same: Nine out of 10 cells in the body are microbes.
Who says?
Everybody.
And they say it everywhere, all the time. But where does the figure come from?
Tabitha M. Powledge tries to track it down in last Friday's On Science Blogs, and I won't spoil the ending.
She also looks at the recent chatter concerning Jean-Baptiste Lamarck, the 18th century scientist who was discredited for his insistence that acquired characteristics can be inherited. He seems to be facing possible vindication in the wake of a Nature study finding that the fears of mice might be inherited by their offspring. Powledge considers the evidence and issues her verdict.
What puzzles me is: Why is this making news now? The story that provoked this comment came from the Society for Neuroscience meeting in San Diego in November. Virginia Hughes drew attention to the story in her National Geographic blog, reporting that researchers had found that mice can inherit the fears of their fathers. (She might have broken the story; most reporters picked it up when the study was published in Nature in early December.) In a follow-up post on Dec. 1, she quoted a researcher who has been pursuing this idea for more than a decade. So why all the excitement?
It depends on how you define news. The idea that epigenetic changes can be passed on to the next generation isn't, strictly speaking, news. But it's news to some, and that's often good enough. I predict this won't be the last time that Lamarck is rediscovered, only to prove controversial all over again.
-Paul Raeburn
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